Quadratic Equation And Inequalities

Let \(\mathrm{S}\) be the set of positive integral values of \(a\) for which \(\frac{a x^2+2(a+1) x+9 a+4}{x^2-8 x+32} < 0, \forall x \in \mathbb{R}\). Then, the number of elements in \(\mathrm{S}\) is :